Medical devices for interventional mri and related methods

Abstract

The disclosure relates to medical devices, methods of performing an interventional medical treatment under MRI, and methods of making a medical device. An example medical device includes an elongate member, a reinforcement member, and a marker. The elongate member has a proximal end, a distal end, and a circumferential wall having an outer surface and an inner surface that defines a lumen. The reinforcement member is disposed within the circumferential wall, extends along a length of the elongate member, is formed of a first material, and has a first susceptibility. The marker is attached to the elongate member, is formed of a second material, and has a second susceptibility that is different from the first susceptibility.

1 . A medical device, comprising:
 an elongate member having a proximal end, a distal end, and a circumferential wall having an outer surface and an inner surface that defines a lumen, wherein the circumferential wall includes an inner tubular member formed of a first polymeric material and an outer tubular member formed of a second polymeric material;   a reinforcement member disposed within the circumferential wall between the inner tubular member and the outer tubular member, extending along a length of the elongate member, and formed of a first material and having a first magnetic susceptibility; and   a passive MRI marker attached to the elongate member and formed of a second material having a second magnetic susceptibility that is different than, preferably greater than, the first magnetic susceptibility.   
     
     
         2 . The medical device of  claim 1 , wherein the first material has a magnetic susceptibility not exceeding 3000 ppm and the second material has a magnetic susceptibility of at least 7000 ppm. 
     
     
         3 . (canceled) 
     
     
         4 . The medical device of  claim 1 , wherein the first material comprises a paramagnetic material and the second material comprises a ferromagnetic material. 
     
     
         5 . The medical device of  claim 1 , wherein the first material comprises a Cobalt Chromium alloy or a Nickel Cobalt alloy. 
     
     
         6 - 8 . (canceled) 
     
     
         9 . The medical device of  claim 2 , wherein the reinforcement member comprises a coil. 
     
     
         10 . The medical device of  claim 9 , wherein the coil is a flat wire coil having a thickness in the range of about 0.03 mm to about 0.15 mm and a width in the range of about 0.25 mm to about 0.5 mm. 
     
     
         11 - 12 . (canceled) 
     
     
         13 . The medical device of  claim 2 , wherein the reinforcement member comprises a mesh. 
     
     
         14 . The medical device of  claim 1 , wherein the passive MRI marker comprises a band of the second material. 
     
     
         15 . The medical device of  claim 14 , wherein the passive MRI marker is disposed between the inner tubular member and the outer tubular member and distal to the reinforcement member. 
     
     
         16 . (canceled) 
     
     
         17 . The medical device of  claim 1 , wherein the passive MRI marker is disposed between the inner tubular member and the outer tubular member, and wherein the passive MRI marker is disposed at a position that longitudinally coincides with a segment of the reinforcement member. 
     
     
         18 - 27 . (canceled) 
     
     
         28 . The medical device of  claim 1 , wherein the outer tubular member has been thermoformed against and around the reinforcement member and against the passive MRI marker and an outer surface of the inner tubular member. 
     
     
         29 . The medical device of  claim 1 , wherein the passive MRI marker is disposed within a thermoformed polymeric material providing a distal tip of the elongate member. 
     
     
         30 . A medical device, comprising:
 an elongate member having a proximal end, a distal end, and a circumferential wall having an outer surface and an inner surface that defines a lumen, wherein the circumferential wall includes an inner tubular member formed of a first polymeric material and an outer tubular member formed of a second polymeric material;   a reinforcement member disposed within the circumferential wall between the inner tubular member and the outer tubular member, extending along a length of the elongate member, and formed of a first material and having a first magnetic susceptibility not exceeding 3000 ppm;   a passive MRI marker attached to the elongate member and formed of a second material having a second magnetic susceptibility that is greater than the first magnetic susceptibility;   wherein the inner tubular member is formed of a lubricious fluoropolymer;   wherein the outer tubular member is formed of a thermoformable polymeric material that has been thermoformed against and around the reinforcement member and against an outer surface of the inner tubular member;   wherein the inner tubular member has a first longitudinal segment that longitudinally co-extends with the reinforcement member along the elongate member;   wherein the inner tubular member has a second longitudinal segment distal of a distal end of the reinforcement member, the second longitudinal segment having an outer surface; and   wherein the elongate member includes a thermoformed polymeric material providing a distal tip of the elongate member extending distally beyond a distal end of the inner tubular member; optionally, wherein the thermoformed polymeric material is bonded to the outer surface of the second longitudinal segment of the inner tubular member.   
     
     
         31 . The medical device of  claim 30 , wherein the passive MRI marker is disposed between the inner tubular member and the outer tubular member, and the outer tubular member has also been thermoformed against the passive MRI marker. 
     
     
         32 . The medical device of  claim 30 , wherein the passive MRI marker is disposed in the thermoformed polymeric material providing the distal tip of the elongate member. 
     
     
         33 . The medical device of  claim 31 , also comprising a second passive MRI marker, wherein the second passive MRI marker is disposed in the thermoformed polymeric material providing the distal tip of the elongate member. 
     
     
         34 . The medical device of  claim 31 , wherein the first material has a magnetic susceptibility not exceeding about 2000 ppm. 
     
     
         35 . The medical device of  claim 30 , wherein the second material has a magnetic susceptibility of at least about 7000 ppm. 
     
     
         36 . The medical device of  claim 30 , wherein the first material is selected from Titanium, Nickel-containing alloys, Cobalt-containing alloys, Cobalt Chromium alloys, tungsten, and a polymeric material. 
     
     
         37 . The medical device of  claim 36 , wherein the second material is selected from nickel, alloys of nickel, iron, alloys of iron, cobalt, and alloys of cobalt. 
     
     
         38 . The medical device of  claim 37 , wherein the outer tubular member is formed of a thermoformable polyamide polymer, and wherein the thermoformed polymeric material providing the distal tip is a thermoformed polyamide material. 
     
     
         39 . (canceled) 
     
     
         40 . The medical device of  claim 38 , wherein the lubricous fluoropolymer is polytetrafluoroethylene. 
     
     
         41 . The medical device of  claim 40 , which is an introducer sheath comprising a proximal hub including an elastomeric seal member for preventing backflow of fluids through the hub. 
     
     
         42 - 43 . (canceled) 
     
     
         44 . The medical device of  claim 30 , wherein the circumferential wall has a wall thickness in the range of about 0.25 mm to about 0.35 mm. 
     
     
         45 . The medical device of  claim 30 , wherein the first material is a superalloy containing nickel, cobalt, chromium and molybdenum. 
     
     
         46 . A method for making a medical device, comprising:
 positioning an elongate reinforcement member around an elongate polymeric inner tubular member, the reinforcement member being formed from a first material having a first magnetic susceptibility;   positioning an elongate thermoformable polymeric outer tubular member around the reinforcement member and inner tubular member;   thermoforming the outer tubular member against and around the reinforcement member and against an outer surface of the inner tubular member to provide an elongate reinforced tubular structure; and   attaching a passive MRI marker formed from a second material to the reinforced tubular structure, the second material having a magnetic susceptibility that is different than, preferably greater than, the first magnetic susceptibility.   
     
     
         47 - 58 . (canceled) 
     
     
         59 . A method for treating a patient, comprising:
 inserting a medical device according to  claim 1  into a region in a patient; and   obtaining an MRI image of the region while the passive MRI marker of the medical device is positioned in the region.   
     
     
         60 . (canceled)